GCSE where 18% was enough to get grade C

Thousands of pupils got a grade C in their chemistry GCSE with a mark of only 18 per cent.

Scientists said the "rogue" paper from the Oxford, Cambridge and RSA board exposed a "major flaw" in the education system.

The marking was revealed in a report by the Royal Society of Chemistry. Nearly 10,700 pupils took OCR's 21st century science higher-tier exam last year. Ninety-five per cent scored at least grade C, having gained only 10 marks from 55. Pupils could score an A* with only 51 per cent of the marks.

The society's chief executive, Dr Richard Pike, said: "Some hard-working pupils are disillusioned through being able to answer correctly less than one-fifth of questions, but are being told they have done well."

But OCR said the threshold for gaining a grade had been lower because the exam was so difficult. "We are disappointed this paper turned out to be too hard," said a spokesman. "It is clear this is an exception."